Equipment for mechanically placing tie plates between rails and rail ties has been proposed in the past. One example of a proposed tie plate placer machine can be found in U.S. Pat. No. 5,655,455 (“the '455 patent”). The tie plate placer disclosed in the '455 patent includes a mobile frame travelling on a railroad track that collects loose tie plates from the rail bed and places them in a magazine for holding and for later positioning on a selected rail tie and underneath the rail. A rail jack lifts the rail away from the tie to allow insertion of the tie plate, and an insertion arm and plate urge a tie plate from the magazine into position between the tie and the rail.
In the device disclosed in the '455 patent, tie plates are retrieved from the rail bed and stored in a collection bed. Operators manipulating magnetic frames sort and orient the collected tie plates into magazines, which are associated with the mechanism that places the tie plates between the rail and the rail ties. Such manipulation of tie plates is susceptible to operator error, and, in part because it requires a dedicated operator for each side of the track during operation, it has an increased cost of operation.
Another example of a known automated tie plate orientation sensor arrangement and a known tie plate sorting and orientation device are shown, respectively, in U.S. Pat. Nos. 4,727,989 (“the '989 patent”) and U.S. Pat. No. 4,907,686 (“the '686 patent”). The device disclosed in the '989 patent is used for determining the current orientation of tie plates using a series of spaced fingers that are pivotable relative to a bar and are arranged across a conveyor carrying the tie plates. Contact between the tie plates and the fingers causes pivotal displacement of the fingers, which act as whiskers to determine the contour and, thus, the orientation of the plates carried by the conveyor. When re-orienting the plates, the device disclosed in the '686 patent includes an inclined conveyor having devices that arrest the descent of individual tie plates along the conveyor. Actuators then flip each tie plate to a correct orientation.
Such and other proposed devices for sensing the orientation of tie plates, whether operating in a manual or automatic fashion, are time consuming and/or involve complicated mechanisms that can be unreliable, inaccurate, costly, and/or inefficient to operate when sorting and orienting tie plates at a high rate for prolonged periods or in inclement weather conditions.